In this paper

several key tests of DC filter capacitors for high voltage direct current（ HVDC） transmission is analyzed. It is thought through analysis of partial discharge that the partial discharge performance of DC filter capacitor is judged by the number of the discharge pulse and this is in agreement with test result; moreover

the issues which shall be considered in the thermal stability test of DC filter capacitor and determination method of test voltage in the AC thermal stability test are proposed; the constructive comments on reversal test method of polarity is proposed by way of analysis of reversal test of polarity and endurance test of DC filter capacitor. It is suggested to perform deep study of aging of full film capacitor under DC voltage.